A semiconductor manufacturing process includes a photoresist process in which a resist is coated onto the surface of a semiconductor wafer (hereinafter referred to simply as a wafer), exposed in a predetermined pattern, and then developed to form a resist pattern. Such a process is generally performed by a system in which a coating-and-developing apparatus for coating-and-developing a resist is connected to an exposure apparatus.
The operation of the developing apparatus disclosed in JP7-263302A will be described with reference to FIG. 17. First, a wafer W is held in a horizontal attitude on a spin chuck 1, and a developer nozzle 11 is positioned such that its small diameter ejection port is located slightly higher than the surface of the wafer W. Then, the developer nozzle 11 is moved in a radial direction relative to the rotational axis of the wafer W while ejecting a developing solution through the developer nozzle 11 and while rotating the wafer W around a vertical axis. This causes the developing solution to be accumulated on the surface of the wafer W in a spiral manner, as shown in FIG. 17(a). Then, the wafer W with the developing solution 12 accumulated on its surface is left for a predetermined developing time (e.g., 60 seconds) to cause “stationary development” of the resist, as shown in FIG. 17(b). After that, a rinse liquid 14 (e.g., deionized water) is supplied to the center portion of the wafer W through a rinse liquid nozzle 13, as shown in FIG. 17(c). As a result, the portions of the resist insoluble in the developing solution remain, forming a predetermined resist pattern.
In the developing apparatus disclosed in JP2001-284206A, the developer nozzle 11 and the rinse nozzle 13 are mounted on the same nozzle arm (not shown) such that they are adjacent each other in the traveling direction of these nozzles, as shown in FIG. 18. When developing the resist on the wafer W, the developer nozzle 11 and the rinse nozzle 13 are moved from the periphery of the wafer W toward the center portion while ejecting a developing solution and a rinse liquid simultaneously through these nozzles and while rotating the wafer W on the spin chuck 1 around a vertical axis. Thus, the resist on the wafer W is developed while removing the developing solution right after it is supplied to the surface of the wafer W by using the rinse liquid.
However, the above developing method suffers from the following problem. When the resist on the wafer W is developed by using a puddle method (i.e., stationary development) disclosed in JP7-263302A that develops the resist with a developing solution accumulated on the wafer W surface, a pullback phenomenon occurs if the amount of developing solution accumulated on the wafer W is too small, since the resist is generally hydrophobic. In this pullback phenomenon, small amounts of liquid, or developing solution, collected in different places on the wafer W pull each other due to surface tension, which may prevent contact between some portions of the resist and developing solution and hence prevent development of these portions. To overcome this problem, a large amount of developing solution must be supplied to the surface of the wafer W. However, this consumes a large amount of developing solution, increasing the manufacturing cost of the semiconductor device.
A puddle-less method (without performing stationary development) disclosed in JP2001-284206A is one of solutions for the foregoing problem. However, if the size of the ejection port of the developer nozzle is reduced to reduce the amount of developing solution consumed, it takes a long time to apply a developing solution to the entire surface of the wafer W, resulting in increase of the developing time. Furthermore, different portions of the wafer W may be in contact with the developing solution for different amounts of time, resulting in degradation of in-plane uniformity of the developing process.
Further, the following problem arises when the developing solution is removed immediately after its application by supplying deionized water through the rinse nozzle disposed adjacent the developer nozzle as disclosed in JP2001-284206A. It is not possible to ensure a developing time long enough to develop a resist having a low dissolution rate in the developing solution. As a result, there occurs under-development, which means that the sides of the bottom portion of a groove formed in the resist film are not sufficiently dissolved and remain. This results in variations in line width of the resist pattern.